Q. Find a number of ways you can fill a 3*3 grid(with four corners defined as a,b,c,d) if u have 3 white marbles 6 black marbles

Option
1)9C3
2)6C3
3)9C3+6C3
4)(9C3+6C3)/3!

• black and white both are identical marbel...so if we take one type marbel from one side. to fill up those position.. so every 1 pos one marbel is needed..so take white marbel...for 9 spaces and 3 marbel..so as per combination it is (9c3) and 6 blank spces,which will be filled up by 1 way...so ways will be=(9c3*1)=9c3 ans
  
• 10 years agoHelpfull: Yes(5) No(4)
• as there are 9 boxes , if you select 3 boxes for the 3 white marbles then automatically the other 6 boxes are occupied by 6 black marbles and all marbles are identical hence 9C3 is answer as order is not taken here
• 10 years agoHelpfull: Yes(3) No(0)
• 9c3+6c3 we will fill with 3 marbel then for next 6 space available that will we filled by 3
• 10 years agoHelpfull: Yes(0) No(2)
• 9C3 ( 1St place 3 marbles ...rest can be place in 1 way i.e 6c6 ..)
• 10 years agoHelpfull: Yes(0) No(0)